1. Field of the Invention
The present invention relates to a high-efficiency power circuit, and more particularly, to a DC-DC boost converter circuit, which is capable of preventing power loss and stabilizing switching elements by implementing soft switching and improving efficiency by adding a charge pumping function, and a method for driving the same.
2. Discussion of the Related Art
A general power supply circuit includes a boost converter circuit for outputting a constant voltage by harmonics reduction and power factor improvement and an output voltage control circuit for receiving an output voltage from the boost converter circuit and outputting a desired output voltage.
A DC-DC boost converter circuit includes an inductor, an output diode, a switching element and a capacitor. In detail, the switching element is connected in parallel between the inductor and the output diode, which are connected in series, and the capacitor is connected to an output port of the diode in parallel. Such a DC-DC boost converter circuit detects zero current of the inductor by a variable frequency operation so as to solve reverse recovery characteristics of the output diode, thereby realizing zero-current switching in the switching element and the output diode.
However, in the DC-DC boost converter circuit of the related art, since a voltage having the same level as an output voltage is applied between both ends of the switching element during a turn-off period of the switching element, a switching element having a large withstand voltage should be used if a high output voltage is necessary. In addition, since loss generated in a switching element for performing hard switching at a high speed is proportional to switching frequency, the loss is increased, in turn reducing efficiency of the converter.
If charge pumping is performed, an output voltage is set to an integer multiple of an input voltage according to the number of capacitors. In order to obtain an output voltage which is equal to or greater than twice an input voltage, since a plurality of capacitors and switching elements must be included, the size of the boost circuit is increased, the configuration of the boost circuit becomes complicated, and the input voltage must be increased.